The high temperatures achieved by kilns bake clay pieces into ceramics. Part of that process is ensuring the clay pieces...

Once a clay piece has been molded into the desired shape, it is allowed to dry and harden. At this point it is still considered a piece of clay. It will not be a ceramic piece until it is fired to a temperature of at least 1200 degrees Fahrenheit. This is because the material must go through a transformation in the heating process that turns clay into ceramic. This is accomplished by heating the piece until the clay begins to turn into glass. Once this occurs, the glass and clay melt together and begin to form ceramic crystals. Once the ceramic crystals have formed, the piece then becomes ceramic pottery.